Effect of lactobacillus postbiotics on entamoeba histolytica trophozoites

ABSTRACT Background Amebiasis is an infectious disease caused by Entamoeba histolytica. It represents one of the three worldwide leading causes of death by parasites and a public health problem due to its frequency, morbidity, mortality, and easy dispersion. Objective The study was aimed to evaluate the in vitro effect of Lactobacillus spp. postbiotics on E. histolytica trophozoites (HM1-IMSS strain) and to determine morphometric changes in trophozoite membrane by atomic force microscopy (AFM). Methods Bioassays on trophozoites were conducted with lyophilized postbiotics at 0.1, 0.3, and 0.5 mg/mL concentrations, and trophozoite samples were obtained for AFM analysis Results Results indicated postbiotic inhibitory activity; the highest percentage inhibition was 89.63% at 0.5 mg/mL. Trophozoites nanomechanical analysis showed 28.32% increase in ruggedness and 56% decrease in size with treatments compared to the control. Conclusion Our study showed that the synergy of Lactobacillus postbiotics inhibited E. histolytica HM1-IMSS in vitro growth under axenic conditions, inducing morphometric alterations in trophozoites’ cell membrane. These results would allow designing strategies or treatments aimed at E. histolytica control in the future.

Degradation of the Transcription Factors NF-kappaB, STAT3, and STAT5 Is Involved in Entamoeba histolytica-Induced Cell Death in Caco-2 Colonic Epithelial Cells

Entamoeba histolytica is a tissue-invasive protozoan parasite causing dysentery in humans. During infection of colonic tissues, amoebic trophozoites are able to kill host cells via apoptosis or necrosis, both of which trigger IL-8-mediated acute inflammatory responses. However, the signaling pathways involved in host cell death induced by E. histolytica have not yet been fully defined. In this study, we examined whether calpain plays a role in the cleavage of pro-survival transcription factors during cell death of colonic epithelial cells, induced by live E. histolytica trophozoites. Incubation with amoebic trophozoites induced activation of m-calpain in a time- and dose-dependent manner. Moreover, incubation with amoebae resulted in marked degradation of STAT proteins (STAT3 and STAT5) and NF-kappaB (p65) in Caco-2 cells. However, IkappaB, an inhibitor of NF-kappaB, was not cleaved in Caco-2 cells following adherence of E. histolytica. Entamoeba-induced cleavage of STAT proteins and NF-kappaB was partially inhibited by pretreatment of cells with a cell-permeable calpain inhibitor, calpeptin. In contrast, E. histolytica did not induce cleavage of caspase-3 in Caco-2 cells. Furthermore, pretreatment of Caco-2 cells with a calpain inhibitor, calpeptin (but not the pan-caspase inhibitor, z-VAD-fmk) or m-calpain siRNA partially reduced Entamoeba-induced DNA fragmentation in Caco-2 cells. These results suggest that calpain plays an important role in E. histolytica-induced degradation of NF-kappaB and STATs in colonic epithelial cells, which ultimately accelerates cell death.

Ultrastructural observation of human neutrophils during apoptotic cell death triggered by Entamoeba histolytica

Neutrophils are important effector cells against protozoan extracellular parasite Entamoeba histolytica, which causes amoebic colitis and liver abscess in human beings. Apoptotic cell death of neutrophils is an important event in the resolution of inflammation and parasite's survival in vivo. This study was undertaken to investigate the ultrastructural aspects of apoptotic cells during neutrophil death triggered by Entamoeba histolytica. Isolated human neutrophils from the peripheral blood were incubated with or without live trophozoites of E. histolytica and examined by transmission electron microscopy (TEM). Neutrophils incubated with E. histolytica were observed to show apoptotic characteristics, such as compaction of the nuclear chromatin and swelling of the nuclear envelop. In contrast, neutrophils incubated in the absence of the amoeba had many protrusions of irregular cell surfaces and heterogenous nuclear chromatin. Therefore, it is suggested that Entamoeba-induced neutrophil apoptosis contribute to prevent unwanted tissue inflammation and damage in the amoeba-invaded lesions in vivo.

Amibiasis intestinal invasora: Patogenia

Las personas que albergan trofozoitos de Entamoeba histolytica no patógena (actualmente denominada Entamoeba dispar) nunca desarrollan formas invasoras de amibiasis, y además, nunca es posible encontrar en su suero antígenos amibianos, razón por la cual tampoco desarrollan una respuesta inmunitaria con producción de anticuerpos antiamibianos. Por el contrario, en aquellas personas que albergan trofozoitos de Entamoeba histolytica patógena si es posible encontrar en el suero antígenos amibianos y evidencia inmunológica del desarrollo de una respuesta del huésped a los mismos; además, desde el punto de vista clínico, estas personas pueden permanecer asintomáticas, según sea la correlación de fuerzas entre parásito, huésped y medio ambiente, dando lugar al estado de portador asintomático cuyas implicaciones clínicas, diagnósticas y terapéuticas fueron revisadas en la pasada entrega de esta revista, o bien pueden desarrollar una amibiasis intestinal invasora cuya patogenia constituye el tema del presente artículo. En una futura entrega se revisará el tema de los síndromes clínicos, diagnóstico y tratamiento de la amibiasis intstinal invasora y de la amibiasis extraintestinal

Interacción del citoesqueleto de E. histolytica con eritrocitos humanos / Interaction of E histolytica cytoskeleton with human red blood cells

La invasión de E histolytica en el colon es medida por el reconocimiento de una lectina en las células intestinales; después de este primer evento los trofozoitos forman úlceras y fagocitan eritrocitos; la destrucción de células de mamíferos por la E histolytica requiere de actina de su citoesqueleto que involucra eventos fagocíticos. En nuestro estudio utilizamos glóbulos rojos humanos para estimular la polimerización de la actina. Para observarla mediante el microscopio de fluorescencia fue necesario lisar la membrana celular con triton X100, fijar con glutaraldehído y teñir con rodamina-phaloidina; después de dos minutos de reto de amibas con eritrocitos, se encontró la máxima polimerización de la actina distribuida en forma de ondas o de anillos. La rodamina- phaloidina es eficaz para unirse a esta proteína y el procedimiento tiene la ventaja de ser menos laborioso que cuando se detecta mediante anticuerpos monoclonales fluorescentes. Mediante el microscopio electrónico de barrido, después de dos minutos de reto, observamos glóbulos rojos adheridos a la membrana de los trofozoitos y, a los cuatro minutos, encontramos la óptima fagocitosis